1. Field of the Invention
The present invention relates to analog conversion devices, and more particularly to a serial-to-parallel analog charge coupled device (CCD) gallium arsenide (GaAs) device for analog-to-digital or digital-to-analog high speed conversion.
2. Description of the Prior Art
High speed analog conversion is desired for high performance instrumentation. Gallium arsenide (GaAs) converters have the capability of high speed operation. Such converters, however, have an aperture window, or delay, which varies from converter to converter. These converters have been cascaded to convert analog signals to digital data by limiting each converter to an amplitude range with the analog signal input to each one simultaneously. When a convert signal is applied to the converters, only that converter whose amplitude range encompasses the amplitude of the analog signal at that instant provides an output. Due to the differences between converters, the outputs from different converters may occur at different times after the convert signal, resulting in inaccuracies, or glitches, when the data are recreated.
A non-realtime technique uses charge coupled devices which are sample and hold storage devices. Data are read rapidly into the CCDs, then during a pause in the data, the data are read out for conversion before the CCDs lose a significant part of their charge.
What is desired is a realtime analog conversion device which operates at high speed without data glitches in the time domain.